1. Field of the Invention
The present invention generally relates to a method of measuring a resistance of a transfer roller, and more specifically, to a method of measuring a resistance of an entire area of a transfer roller rotating at least one revolution, by applying a testing voltage to the transfer roller.
2. Description of the Related Art
Conventionally, an image forming apparatus, such as a printer and/or a copier, has a transfer unit to transfer an image, which was developed in a photoconductive unit including a photoconductive medium, on a transferring medium such as a paper. The transfer unit has a transfer belt rotating on an endless track.
Plural rollers support the transfer belt and include a drive roller to generate a driving force for the transfer belt. When the image formed on the transfer belt is to be transferred to the transferring medium, the transfer roller contacts a side of the transfer belt. Next, a high voltage is applied to the transfer roller so that the image on the transfer belt is transferred onto a recording medium, such as a paper.
Meanwhile, when the high voltage is applied to the transfer roller, the transfer belt is temporarily rotating prior to the drive of the transfer unit to set an appropriate high voltage. Next, by applying a testing voltage to the transfer roller contacting the driving transfer belt, an average resistance is measured.
However, if the high voltage as the testing voltage is continually applied to a specific area of the transfer belt, the transfer belt develops an electrical fatigue, and due to this electrical fatigue, the transfer belt becomes stressed. As a result, stripes are formed on the transfer belt.
The stripes formed on the transfer belt may result in a difference of optical density of the image transferred on the recording medium, thus contaminating the transferred image. Thus, it is hard to form a high-resolution image.